Blood glucose testing offers little value to some Type 2 diabetes patients: study

When Margaret DeNobrega was first diagnosed with Type 2 diabetes, she meticulously monitored her eating habits and blood sugar levels.

The68-year-old would write down what she ate for breakfast, lunch and dinner, pricking her finger to test her glucose levels before and after each meal.

"I used to test before my meals, so I would know what my blood sugar was at, and then I would test two hours after," she says. "I did that for quite a while.

"I guess maybe I did obsess a little about it because I didn't want to go on medication."

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It's a daily ritual for many with Type 2 diabetes, aimed at helping them keep their blood sugar levels in check. But according to a new U.S. study, that common finger-prick test may have little impact on managing the chronic condition.

Type 2 diabetes is one of the fastest-growing diseases in Canada, with about 60,000 new cases diagnosed each year.

Complications associated with the disease including kidney disease, heart disease, blindness and stroke can range from serious to life-threatening, making proper management of blood sugar levels important.

Insulin-dependent patients will frequently test their blood sugar before delivering a shot of the hormone.

But the majority of Type 2 patients aren't treated with insulin, and can instead regulate their glucose levels through diet, exercise and sometimes medication.

Rejecting routine testing

In a paper published this week in JAMA Internal Medicine, researchers found that self-monitoring of blood sugar for non-insulin Type 2 patients offers virtually no benefit.

"From the study, what we find is that glucose monitoring should not be routine," Dr. Katrina Donahue, one of the study's authors, told CBC News.

To conduct the study, the researchers tested 450 adult patients with Type 2 diabetes in North Carolina. None were being treated with insulin and all had baseline A1C levels (glycated hemoglobin) between 6.5 and 9.5 per cent, considered fair.

The patients were then divided into three groups:

• No self-monitoring of blood glucose.
• Once-a-day monitoring.
• Enhanced once-a-day monitoring, with the meter delivering automated messages of encouragement or instruction.

One year later, there were "no significant differences" across the groups when it came to glycemic control, health-related quality of life, or hospitalizations or ER visits.

"We were not able to find a difference in the health outcomes we were looking at," says Donahue. "We did not find harms, nor did we find benefits."

'Negative impact'

It's a finding that came of little surprise to Dr. Kimberly Wintemute. The Toronto-based family physician says there have been several studies showing that at-home glucose testing doesn't add value to a Type 2 patient's care.

"People who test their sugar regularly give scores that are about on par with people who have had a recent stroke," says Wintemute, who is also co-lead of Choosing Wisely Canada, a campaign aimed at reducing the use of unnecessary health care.

"So not only does it not change the overall blood-sugar control, it has a negative impact on the way that people perceive their health and their quality of life."

Wintemute says she believes patients have been conditioned to believe that more data is going to mean better results. But testing can also create anxiety for patients who may obsess about their numbers, and the test strips can be costly.

Instead, she says those with Type 2 diabetes should focus on everyday activities known to improve overall health: things like exercising daily, managing portion sizes at meal times, and avoiding smoking and drinking.

Monitor when introducing new meds

Some provinces, including Ontario, Manitoba,B.C., and Newfoundland and Labrador, have already limited funding for test strips for non-insulin dependant diabetics a move that Wintemute says brings them "in line with the science."

Glucose monitoring is important for newly diagnosed patients, she adds, as well as when a new medication is introduced or a dosing measure changed. And anyone on insulin needs to be testing regularly.

"So it's not never to test; it's just that there are very specific circumstances where we know testing can be of value," she says.

DeNobrega, who was first diagnosed 15 years ago, says while she doesn't test nearly as much as she used to she now knows how a piece of fruit is going to affect her it remains an important part of her managing her diabetes.

She says she would hate to abandon her blood-glucose meter altogether.

"For me, I think testing is important," she says. "If I feel I have sort of gone off my diet, or I haven't exercised as much, I would want to test my sugar to see what that has done.

"It is a comfort thing."

For its part, the Diabetes Canada website recommends self-monitoring of blood glucose, but adds that patients should talk to their doctors.